Predictive Models for Damping in Buildings: The Role of Structural System Characteristics

Damping is dependent on many variables and complex mechanisms that are not yet fully quantifiable in the design stage. This has led to generic assignments of viscous damping usually based on material type and at best based on height with reference to existing databases. This study will employ recent full-scale observations to demonstrate the role of the structural system's dominant deformation mechanism — frame racking vs. cantilever action — in energy dissipation capability. Specifically, it is shown that frame racking and other shear deformations dissipate more energy than the axial shortening associated with cantilever action. As such, the ratio of frame racking to cantilever action may offer a more robust and intuitive parameter better suited for use in predictive viscous damping models. This study serves as the first step in the development of such models, with a specific focus on serviceability design.